1. Field of Invention
The invention generally relates to testing and calibration of optical and electro-optical modules, generically referred to herein as xe2x80x9cmodulesxe2x80x9d or xe2x80x9coptical modules.xe2x80x9d More specifically, the invention relates to systems, apparatuses and methods for performing parallel, asynchronous testing and calibration of optical and/or electro-optical modules.
2. Description of Related Art
Electronic manufacturers that produce large volumes of identical components have sought to improve widely-used serial testing techniques by employing parallel testing schemes. Such parallel test schemes subject a large number of identical electronic devices to the same test. The test cycle for such electronic components is relatively short and the testing of a plurality of such components is initiated simultaneously. In other words, there is known a synchronous, parallel testing scheme for testing electronic components.
Optical networking equipment manufacturing presents difficult challenges not faced by electronic equipment manufacturers. It is quite common for optical networking equipment manufacturers to specially build a set of optical networking equipment to order. Furthermore, the orders are often unpredictable and sporadic which means that the manufacturing must be highly adaptable and dynamic.
In other words, optical networking equipment manufacturing is a high mix environment in which a variety of different modules are made. The mix of equipment may change on a daily or even hourly basis. This is particularly true for WDM (wave division multiplexed) or DWDM (dense wave division multiplexing) equipment in which a large number of, for example, transmitters, receivers, and transceivers are built each of which may have a different construction and may be designed for a different channel wavelength. Thus, it is inefficient to dedicate a production line or testing station to a particular module or component.
The conventional method of manufacturing optical and electro-optical components and modules is essentially a serial process. For example, a component or module is partially assembled, then tested, then more fully assembled, then tested again, and so on in a sequential fashion. Such serial assembly and testing is inefficient and labor intensive.
Typically, test stations are used to test a component or module in the assembly line. Such test stations are designed to perform a specific test or set of tests in sequence. The test station and the test sequence is specific to the product or assembly line. As such, the typical test station is not flexible and leads to inefficient utilization of test equipment and labor resources. Furthermore, the high mix environment faced by optical networking equipment manufacturers makes using a parallel testing architecture inadequate since different tests needs to be performed on the high mix of components.
The invention may be characterized as an optical module calibration system for calibrating a plurality of optical modules, including: a plurality of optical test signal generators each capable of outputting an optical test signal; a plurality of input switches each optically communicating with the optical test signal generators and a corresponding one of the optical modules to be tested; a plurality of optical signal measuring instruments; a plurality of output switches each optically communicating with the optical signal measuring instruments and a corresponding one of the optical modules to be tested; and a controller operatively connected to the optical modules, the optical test signal generators, the input switches, the output switches, and the optical signal measuring instruments, the controller controlling the optical modules, the optical test signal generators, the input switches, the output switches, and the optical signal measuring instruments to calibrate the plurality of the optical modules.
Furthermore, at least some of the optical signal measuring instruments may be optical power meters each optically communicating with a corresponding one of the input switches and measuring an input optical power input to a corresponding one of the optical modules; the controller using input optical power measurements received from the optical power meters to send commands to the optical modules for calibrating the optical modules.
The controller may also receive data from the optical modules indicative of the respective optical module""s reception of the optical test signal. This controller may also calibrate the optical modules according to the input optical power measurements received from the optical power meters and the data received from the optical modules.
In addition to calibration, the controller may also diagnose the optical modules based on the input optical power measurements received from the optical power meters and the data received from the optical modules.
Furthermore, the invention may use a plurality of variable optical attenuators each optically interposed between a corresponding one of the input switches and a corresponding one of the optical modules; each of the variable optical attenuators also optically communicating with a corresponding one of the optical power meters; the controller also operatively connected to the variable optical attenuators; and the controller also commanding the variable optical attenuators to adjust input optical power levels received by corresponding optical modules.
Still further, the calibration switches may each include a corresponding one of the variable optical attenuators and optically interposed between a corresponding one of the input switches and a corresponding one of the optical modules; each of the calibration switches having a signal output port optically communicating with a corresponding one of the optical modules and a calibration output port optically communicating with a corresponding one of the optical power meters; and the controller also operatively connected to the calibration switches.
The controller may also control the calibration switches to alternately supply the optical test signals to a corresponding one of the corresponding optical modules.and to a corresponding one of the optical power meters; receive input optical power measurements from the optical power meters indicative of the input optical power supplied to the optical modules; utilize the received input optical power measurements to control the variable optical attenuators to adjust the input optical powers of the optical test signals to a next desired power level when the calibration switches alternately supply the optical test signals to the optical power meters; and controller receive data from the optical modules indicative of the respective optical module""s reception of the respective optical test signal.
Another capability of the invention is to tune each of the optical power meters and the optical test signal generators to a corresponding wavelength. This is particularly useful for optical modules having differing operating wavelengths.
The controller may also use the output optical power measurements received from the optical power meters to send commands to the optical modules for calibrating the optical modules.
Output calibration is another feature of the invention. To enable output calibration, the controller may receive data from the optical modules indicative of the respective optical module""s output optical signal power. More specifically, the controller may calibrate the optical modules according to the output optical power measurements received from the optical power meters and the data received from the optical modules. Furthermore, an optical signal degrader may be used to degrade a corresponding optical test signal to a desired signal-to-noise ratio.
Wavelength tuning is also possible with the invention if at least some of the optical signal measuring instruments are wavelength meters each measuring an output wavelength output by a corresponding one of the optical modules. The controller may use output wavelength measurements received from the wavelength meters to send commands to the optical modules for calibrating the optical modules.
Moreover, the controller may control the optical test signal generators, the input switches, the output switches, and the optical signal measuring equipment to perform parallel asynchronous calibration of the optical modules.
Further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the spirit and scope of the invention will become apparent to those skilled in the art from this detailed description.